Thiodiphenol copolycarbonates and their use as components of multilayered polymeric reflective bodies

ABSTRACT

This invention provides novel copolycarbonates that exhibit improvements in glass transition temperature, refractive index, and limiting oxygen index compared to prior art thiodiphenol/bisphenol A copolycarbonates. The copolycarbonates of this invention comprise the reaction products of 4,4&#39;-thiodiphenol and compounds such as 9,9-bis (4-hydroxyphenyl) fluorene with phosgene. They are useful as components of multilayered polymeric reflective bodies.

BACKGROUND OF THE INVENTION

This application is a continuation of PCT/US93/06074.

This invention relates generally to copolycarbonates; their method ofpreparation; their use in preparing improved polymeric bodies; and theimproved polymeric bodies. More specifically, the invention concernsnovel 4,4'-thiodiphenol (TDP) copolycarbonates having properties thatmake them particularly suitable for preparing certain types ofmultilayered polymeric bodies.

U.S. Pat. Nos. 5,122,905 and 5,122,906 teach the use of polycarbonatesin preparing highly reflective multilayered polymeric bodies. The onlypolycarbonate it specifically discloses in its Examples is ahomopolycarbonate of bisphenol A (Calibre 300-22, trademark of The DowChemical Company). We concluded that it would be desirable to providematerials with improvements in glass transition temperature (Tg),refractive index (RI), and limiting oxygen index (LOI). Such materialswould significantly expand the application areas for the multilayeredpolymeric bodies.

In addition, several recent published patent applications teach the useof (previously known) copolycarbonates of 4,4'-thiodiphenol (TDP) andbisphenol A (BA) as the high refractive index (RI) component of amultilayered polymeric reflective body.

SUMMARY OF THE INVENTION

This invention provides novel copolycarbonates that typically exhibitthe desired improvements in Tg, RI, and LOI compared to the prior artTDP/BA copolycarbonates (and BA homopolycarbonates). More particularly,this invention provides novel copolycarbonates of TDP and at least onemember of the group consisting of 9,9-bis (4-hydroxyphenyl) fluorene(BHPF); 1,1-bis (4-hydroxyphenyl)-1-phenyl ethane (bisphenol AP, BAP);phenolphthalein (PP); bis (4-hydroxyphenyl) diphenyl methane (BHDM);tetrabromobisphenol A (TBBA); and tetrachlorobisphenol A (TCBA).

A first broad aspect of the invention is a copolycarbonate of4,4'-thiodiphenol and at least one member of the group consisting of9,9-bis (4-hydroxy-phenyl) fluorene; 1,1-bis (4-hydroxyphenyl)-1-phenylethane; phenolphthalein; bis (4-hydroxyphenyl) diphenyl methane;tetrabromobisphenol A; and tetrachlorobisphenol A.

A second broad aspect of the invention is a multilayered polymericreflective body wherein the highest refractive index component is acopolycarbonate of 4,4'-thiodiphenol and at least one member of thegroup consisting of 9,9-bis (4-hydroxyphenyl) fluorene; 1,1-bis(4-hydroxyphenyl)-1-phenyl ethane; phenolphthalein; bis(4-hydroxyphenyl) diphenyl methane; tetrabromobisphenol A; andtetrachlorobisphenol A.

A third broad aspect of the invention is a process for makingcopolycarbonates comprising reacting 4,4'-thiodiphenol and at least onemember of the group consisting of 9,9-bis (4-hydroxyphenyl) fluorene;1,1-bis (4-hydroxyphenyl)-1-phenyl ethane; phenolphthalein; bis(4-hydroxyphenyl) diphenyl methane; tetrabromobisphenol A; andtetrachlorobisphenol A with a carbonate precursor under conditionssufficient to cause reaction.

DETAILED DESCRIPTION OF THE INVENTION

In the practice of this invention the copolycarbonate advantageouslycomprises from 10 to 80 mole percent TDP. In the most preferredembodiment of the invention TDP is copolymerized with BHPF. Methods ofproducing polycarbonates are well known in the prior art. Such methodsare also suitable for use in forming the copolycarbonate compositions ofthe present invention. Suitable methods for preparing polycarbonates areset forth in U.S. Pat. Nos. 3,248,414; 3,153,008; 3,215,668; 3,187,065;3,028,365; 2,999,846; 2,999,835; 2,964,974; 2,970,137; and 1,991,273.The copolycarbonates of the present invention are prepared by thereaction of the bisphenol mixture with a carbonate polymer precursor,which may include either a carbonyl halide, a diaryl carbonate, adialkyl carbonate, or a bishaloformate.

This invention is further illustrated by the following examples.

EXAMPLE 1 (INCLUDING TYPICAL PREPARATION)

This example describes the synthesis of a 50/50 molar ratiocopolycarbonate of TDP and BHPF. A 5 L 4-neck roundbottom flask equippedwith a thermometer, condenser, phosgene/nitrogen inlet, and a paddlestirrer connected to a Cole Parmer servodyne was charged with TDP(105.52 g, 0.484 mol), BHPF (169.40 g, 0.484 mol), 4-tertbutylphenol(2.18 g, 14.5 mmol, 1.5 mol % based on bisphenols), pyridine (199.0 g,2.516 mol), and methylene chloride (2.36 L). The mixture was stirred at250 rpm and slowly purged with nitrogen as phosgene (95.8 g, 0.968 mol)was bubbled in over 50 minutes while maintaining the reactor temperatureat 20° to 24° C. An additional 4.0 g of phosgene was then added over aperiod of 7 minutes.

The reaction mixture was worked up by adding methanol (5 mL) and then 3NHCl (3.6 L). After stirring for 15 minutes, the mixture was allowed tostand overnight. The methylene chloride layer was separated and washedfurther with 0.5N HCl (0.42 L), water (0.4 L), and was then passedthrough a column of MSC-1-H ion exchange resin (0.5 L bed volume). Thecopolymer was isolated by adding 0.9 L of this purified methylenechloride solution to a mixture of 1.2 L hexane and 2.4 L acetone in anexplosion resistant Waring blender. The product was filtered, dried in ahood overnight, and then dried for 48 hours in a vacuum oven atapproximately 120° C. The resulting copolycarbonate weighed 267.7 g, hadan inherent viscosity (IV) of 0.52 dL/g (determined in methylenechloride at 0.5 g/dL and 25° C.), and exhibited an extrapolated onset Tgof 215° C. (determined by DSC at a scan rate of 20° C./minute). ¹ H NMRanalysis was in agreement with the 50/50 TDP/BHPF monomer feed ratio. Acompression molded plaque, prepared at 320° C., had a RI of 1.650 whenmeasured at 600 nm.

EXAMPLES 2-7

Additional copolycarbonates of the type TDP/X were prepared over a rangeof molar ratios and essentially according to the general procedure ofExample 1 except the bisphenol X was selected from BHPF (Example 2), BAP(Example 3), PP (Example 4), TBBA (Example 5), TCBA (Example 6), andBHDM (Example 7). These compositions and the results for IV, Tg, RI, andLOI are summarized in Table 1. LOI measurements were performed oncompression molded specimens (0.125 inch thickness, molded atapproximately 100° C. above Tg) according to ASTM Test Method D-2863.For comparison, results are also shown for prior art TDP/BAcopolycarbonates. As evidenced by the results of Table 1, the new TDPcopolycarbonates of this invention (Examples 2-7) provide significantimprovements in Tg, RI, and LOI compared to corresponding TDP/BAcopolycarbonates (Comparative Example).

                                      TABLE 1                                     __________________________________________________________________________                               RI                                                 Ex. No.                                                                            Diol X                                                                             Mole % X                                                                            IV (dL/g)                                                                           Tg (°C.)                                                                    (at 600 nm)                                                                         LOI (% O.sub.2)                              __________________________________________________________________________    Comp.                                                                              BA*  25    0.51  125  1.636 46.9                                                   50    0.54  135  1.614 37.2                                                   75    0.56  140  1.601 29.0                                         2    BHPF 25    0.49  165  1.651 58.0                                                   50    0.37  207  1.652 NM                                                     50    0.60  216  1.649 59.7                                                   75    0.57  253   NM** NM                                           3    BAP  25    0.51  139  1.642 49.5                                                   35    0.48  146  1.635 NM                                                     50    0.46  154  1.627 42.5                                                   75    0.50  175  1.618 39.5                                         4    BHDM 25    0.47  148  1.647 NM                                           5    TBBA 15    0.48  143  NM    NM                                                     20    0.41  149  NM    NM                                                     25    0.39  154  1.642 NM                                                     50    0.40  196  1.634 NM                                                     75    0.54  234  NM    NM                                           6    TCBA 25    0.42  147  NM    NM                                                     50    0.43  179  NM    NM                                                     75    0.34  200  NM    NM                                           7    PP   25    0.46  152  NM    NM                                                     50    0.52  197  NM    NM                                                     75    0.44  223  NM    NM                                           __________________________________________________________________________     *Not an example of this invention.                                            **NM = not measured.                                                     

As can be seen these polymers possess very desirable combinations ofphysical and optical properties, particularly the high refractive indexand good heat resistance and processing temperatures. These and otherproperties make the polymers according to the present invention wellsuited to be employed as layers of varying thickness in multi-layeredstructures, optionally also comprising other features, to achieveselected transmission, reflective and other optical effects.

Examples of these applications for the compositions according to thisinvention include use as a high refractive index layer in the reflectivepolymeric bodies as shown in U.S. Pat. Nos. 5,122,905; 5,122,906;5,217,794 and 5,126,880. Among the benefits obtained using thesematerials in these and other types of structures are the ability toprovide greater differences in refractive index versus another givenpolymer and the corresponding benefits of obtaining increasedreflectance for a given number of layers or obtaining equivalentreflectance with less layers.

It is also possible to employ the polymers according to this inventionas a high refractive index layer of an appropriate thickness to suppresshigher order reflectance as is shown in the visibly transparent infrared(IR) reflective films in U.S. Pat. No. 5,103,337. These materials aresimilarly suitable for use as high refractive index layers in otherspectrally selective reflectors. These polymers can also suitably beemployed as a high refractive index layer in the tamper evident films asshown in U.S. Pat. No. 5,149,578; in the covert signature films as shownin U.S. Pat. No. 5,095,210; and in the birefringent interferencepolarizer films as shown in EP 488,544.

Various modifications may be made in the present invention withoutdeparting from the spirit or scope thereof as will be evident to thoseskilled in the art.

What is claimed is:
 1. A copolycarbonate of 4,4'-thiodiphenol and9,9-bis (4-hydroxyphenyl) fluorene.
 2. A copolycarbonate of claim 1comprising 4,4'-thiodiphenol in an amount of from 10 to 80 mole percentof the copolycarbonate.
 3. The copolycarbonate of claim 1 comprising thereaction product of (a) a carbonate polymer precursor selected from thegroup consisting of a carbonyl halide, a diaryl carbonate, a dialkylcarbonate and a bishaloformate; (b) 4,4'-thiodiphenol; and (c) 9,9-bis(4-hydroxyphenyl) fluorene.
 4. A multilayered polymeric reflective bodywherein the highest refractive index component is a copolycarbonate of4,4'-thiodiphenol and 9,9-bis (4-hydroxyphenyl) fluorene.
 5. Amultilayered polymeric reflective body wherein the highest refractiveindex component is a copolycarbonate comprising the reaction product of(a) a carbonate polymer precursor selected from the group consisting ofa carbonyl halide, a diaryl carbonate, a dialkyl carbonate and abishaloformate; (b) 4,4'-thiodiphenol; and (c) 9,9-bis (4-hydroxyphenyl)fluorene.